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ANTIINFECTIVES FOR SYSTEMIC USE › ANTIBACTERIALS FOR SYSTEMIC USE › OTHER ANTIBACTERIALS › Polymyxins
polymyxin B
J01XB02
Forms & Strengths
- Injection: 500,000 units per vial (as polymyxin B sulfate)
- Ophthalmic: 10,000 units/mL with neomycin and gramicidin
- Topical: 10,000 units/g with bacitracin or neomycin
Adult Dosing
- Intravenous: 15,000 to 25,000 units/kg/day divided every 12 hours
- Intrathecal: 50,000 units once daily for 3-4 days, then every other day
- Max daily dose: 2,000,000 units/day
Pediatric Dosing
- Infants and children IV: 15,000 to 40,000 units/kg/day divided every 12 hours
- Adjust dose based on ideal body weight in obese patients
- Intrathecal (children > 2 years): 20,000 units once daily for 3-4 days, then 25,000 units every other day
Indications
- Acute infections caused by susceptible strains of Pseudomonas aeruginosa
- Meningitis caused by susceptible strains of Pseudomonas aeruginosa (intrathecal)
- Urinary tract infections, meningeal infections, and septicemia caused by susceptible gram-negative organisms when less toxic drugs are ineffective
Mechanism of Action
- Binds to phospholipids in the bacterial cytoplasmic membrane
- Alters membrane permeability, leading to leakage of intracellular components and cell death
- Bactericidal against susceptible gram-negative bacilli
Contraindications
- Hypersensitivity to polymyxins
- Concurrent use of other nephrotoxic or neurotoxic drugs when avoidable
Adverse Reactions
- Nephrotoxicity (albuminuria, cellular casts, azotemia)
- Neurotoxicity (facial flushing, dizziness, ataxia, drowsiness, neuromuscular blockade, apnea)
- Local irritation and thrombophlebitis at injection site
Drug Interactions
- Neuromuscular blocking agents (enhanced and prolonged respiratory depression)
- Nephrotoxic drugs such as aminoglycosides, vancomycin, and amphotericin B (increased risk of renal toxicity)
- Other neurotoxic agents (additive neurotoxicity)
Curated Content: Needs Vetting Before Put to Clinical Use